The invention relates to an emissions analyzer which analyzes the concentration of various gases in the exhaust stream of an internal combustion engine, and more specifically to an automatic gain control for the infrared source used in such an emissions analyzer.
Heretofore, infrared radiation sources have been constructed with a relatively large mass which results in a long warm-up time for the analyzer to stabilize, particularly from a cold start condition.
It is the primary object of the present invention to provide a radiant-energy infrared source which has a fast warm-up time beginning from a cold start. This is achieved by automatic gain control of the infrared source.
It is yet another object of the present invention to provide a constant infrared energy output from a radiant energy source, despite a cooling effect from an airdraft impinging the source element or the effect of changing ambient temperature or other environmental factors that would lead to a change in the infrared energy emitted by the source, and consequently the signal output of the infrared detectors used in the equipment.